1. Field of the Invention
The present invention is related to a video signal recording apparatus and method used for recording or transmitting a video signal using bit rate reduction.
2. Description of the Prior Art
One known method of reducing the data amount of a video signal uses bit rate reduction coding. Bit rate reduction is a coding method for reducing the data amount by removing the features of the video signal.
One specific bit rate reduction method forms blocks of plural adjacent pixels and compresses the data by performing an orthogonal transform on each data block. The blocks to which this orthogonal transform is applied are called the "orthogonal transform blocks." To improve the compression efficiency of this orthogonal transformation data, variable length coding is applied to each of the orthogonal transform blocks prior to recording or transmission (W. Chen and C. H. Smith: "Adaptive Coding of Monochrome and Color Images," IEEE Trans. Commun., COM-25, 11, pp. 1285-1292 (Nov. 1977)).
However, if variable length coding is used and a playback error occurs, it is not possible to decode the data following the error. In addition, the data can also be reproduced only within a narrow band during high speed (trick) playback modes on a conventional video cassette recorder (VCR). Decoding of more data is not possible in this case because it is not clear where on screen the decoded (reproduced) data is to be displayed. It is therefore difficult to use variable length coded data with conventional VCRs.